This invention relates to voltage controlled electronic displays.
One type of voltage controlled display is an electrophoretic display device such as described in xe2x80x9cAll Printed Bistable Reflective Displays: Printable Electrophoretic Ink and All Printed Metal-Insulator-Metal Diodesxe2x80x9d Massachusetts Institute of Technology June 1998 and provided by E-INK, Inc. Cambridge, Mass. This type of display is based on so called xe2x80x9celectronic inks,xe2x80x9d e.g., electrophoretic materials that change their properties based on an applied voltage. Using electrophoretic materials such as electronic ink, a flat panel display can be printed on a substrate material. These displays draw very little current and hence dissipate very little power. Any voltage sensitive material could be used as the display. Another material that has described in xe2x80x9cThe Reinvention of Paperxe2x80x9d, Scientific American, September 1996, called Gyricon which is also voltage sensitive. Both of these types of displays operate at relatively high voltages.
A metal-insulator-metal diode (M-I-M) diode exhibits current-voltage characteristics similar to a semiconductor diode. One distinction from semiconductor diode current-voltage characteristics is that the current-voltage characteristics of a M-I-M diode are symmetrical. Typical the current-voltage characteristic curve of an M-I-M diode is bipolar. That is, at a predetermined negative voltage and a substantially the same predetermined positive voltage, the diode can switch between non-conducting and conducting states.
One type of metal-insulator-metal diode includes a composite metal-insulating layer that spaces two conductive layers, i.e., electrodes. The composite metal/insulating layer has an insulating binder, suspending metal particles having a relatively thick, thermally grown or deposited oxide layer on the metal particles. In the above thesis of Jaeyong Park two types of processes for producing such metal-insulator-metal diodes are described. The diodes produced from this work exhibit relatively high switching voltages.
According to an aspect of the present invention, a voltage controlled display includes a display element having a pair of electrodes and a voltage divider having a terminal coupled to a first one of the pair of electrodes of the voltage controlled display. The voltage controlled display also includes a metal-insulator-metal diode having a switching voltage less than about 10 volts coupled to the voltage divider. The voltage controlled display of claim 1 wherein the voltage divider includes a pair of resistors having the same resistance.
The voltage controlled display can have a voltage potential at the first terminal of the display element that is a fraction of a signal line voltage and a potential at the second terminal of the display element determined by a voltage across the nonlinear element and resistor. The voltage controlled display can include a second metal-insulator-metal device coupled in series with a resistor coupled. In this arrangement, a voltage potential at the first terminal of the display element is a fixed, fraction of a signal line voltage and a potential at the second terminal of the display element is determined by a voltage at a connection of the nonlinear element and resistor.
According to an additional aspect of the present invention, a voltage controlled display includes a plurality of display cells coupled in an array. Each cell of the array includes a display element having a pair of electrodes, a voltage divider having a terminal coupled to a first one of the pair of electrodes of the voltage controlled display and a metal-insulator-metal diode having a switching voltage less than about 10 volts coupled to the voltage divider.
One or more of the following advantages may be provided by one or more aspects of the invention. One advantage of the display compared to other displays is that is uses very little current and switches at low voltages. The display includes a voltage sensitive display and low voltage switching nonlinear element e.g., a low voltage metal-insulator-metal diode (M-I-M diode). The voltage sensitive display uses a material that switches based on the voltage. In addition, the display array, elements, resistors and nonlinear devices can all be fabricated using conventional and inexpensive printing techniques.